Method of and apparatus for desulphurizing oil



Jan. l, 1935. J. H. ERTER METHOD OF AND APPARATUS FOR DESULPHURIZING OILFiled June l2, 1930 mlm.

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mw MQ mn ww MN Km Rw SQ m ma NQ a `m Nw mw uw Nm. E ow @n nh PatentedJan. 1, 1935 UNirED STATES y METHOD OF AND APPARATUSFOR DESULPHURIZINGOIL John H. Erter, Elizabeth, N. J., assixnor to Foster WheelerCorporation, New York, N. Y., a corporation of New York Application June12, 1930, Serial No. 460,594

9 Claims.

My invention relates to the art of oil fractionation anddesulphurization and has special reference to the desulphurization ofoils which have a high sulphur content.

Difficulties have been encountered in the removal of sulphur fromsulphur bearing oils by pyrolysis due to the corrosive effects of thesulphides on fractionating towers.

It is also known that the vapors from a fractionating tower may bedesulphurized by contacting them with a catalytic agent, such as clay orfullers earth. However, this contacting must take place at hightemperature in order to causel desulphurization which means that thevapors must be superheated or the oil withdrawn as a liquid stream mustbe revaporized and superheated. Such a process has proved to beuneconomical.

It has occurred to me that, if the crude sulphur bearing oil is mixedwith a catalytic agent prior to heating and is then flashed into afractionating tower, the sulphur will be removed from the oil in theform of hydrogen sulphide gas. This hydrogen sulphide at temperaturesabove approximately 400 degrees F. has a corrosive action on steel andhence to prevent the destruction of the steel shell and any other steelparts of the fractionating tower I line the tower with a nonmetalliclining and use bubble trays and stripping section members made of castiron which is highly resistant to hydrogen sulphide.

I believe that the desulphurization of crude oil is selective as totemperature, that is to say, that different fractions are desulphurizedat different temperatures and I believe that as the oil passes through azone of progressively increasing temperature in the heater along withthe catalytic agent the different fractions are desulphurized at theproper temperatures. Furthermore, it appears that the desulphurizationtemperature of the lighter fractions is higher vthan that of the heavierfractions and a point is reachedtwhere the desulphurization temperatureis lower than the boiling point at atmospheric pressure and, inasmuch asdesulphurization must take place with the oil in the vapor phase, itbecomes necessary to carry on the desulphurization of the heavierfractions under a reduced pressure.I

My invention including the method and apparatus for carrying it intoeffect will be clear and further objects and advantages will be apparentfrom the following description, taken in connection with theaccompanying drawing showing a distillation plant embodying theinvention and which drawing is to be considered a part of thisspecication.

Referring to the drawing, reference character 10 designates a mixingtank, of which there may be several, provided with a mechanical stirring6 device 11 driven by belt 12. A supply conduit 13 is connected to tank10 while a discharge conduit 14 provided with a hand valve 15 connectsthe tank with a pump 16. Pump 16 is connected by means of a conduit 17with an oil heater 18 from which oil is discharged through a conduit 19to Within the ash zone of tower 20. A superheater may be incorporated inthe setting of heater 18, which is supplied with steam through a conduit21 and which discharges superheated steam through a conduit 22.

Tower 20 comprises a steel shell 21' which is preferably linedthroughout with a non-metallic lining 22' of suitable nature to resistthe action oi.' hydrogen sulphide at high temperatures. A 'ceramiclining may be employed comprising a clay composition. Before the liningis placed in the shell, the latter is provided with suitable cast ironbrackets, as is shown at 23, for supporting bubble trays and strippingsections. The lining is then sprayed onto the interior of the `shell andforms a coating therein and also coats the brackets. The coating formedon the brackets may be chipped oi from that portion of the latter whichare to be secured to the bubble trays and stripping sections. Thus thesteel shell is completely covered and protected from the corrosiveaction of the hydrogen sulphide. While it is only necessary to line thetower up to a point above which the temperature is below D degrees F., Iprefer to completely line the tower in order to be certain that it willnot be injured by corrosion.

Conduit 19 discharges into the tower against a perforated baffle 24 madeof cast iron. Below baille 24 are placed suitable bubble trays 25. Abranch of steam conduit 22 enters the bottom of the tower below thelowermost bubble tray 25. The vportion of the tower above baille 24 isoccupied by bubble trays 26 and stripping sections 27 and 2'7.

A conduit 28 communicates with the top of the tower and leads to acondenser 29 which is in turn connected by means of a conduit 30 withcooler 31. A conduit 30 is connected to conduit 30 and serves tointroduce water or a neutralizing agent into the latter for purposeshereinafter to be described. Cooler 31 is connected by means of aconduit 32 with an accumulator tank 33. A conduit 34 communicates withtank 33 at a point somewhat above conduit 32 and extends to a refluxpump 35, the discharge of which is connected by means of a conduit 36 tothe upper part of tower 20 above the uppermost bubble tray therein.

Conduits 37 and 38 communicate with stripping -sections 27 and 27',respectively, for conveying side streams from the tower. Steam mayI besupplied to stripping `sections 27 and 27 through conduit 22.

Accumulator tank 33 is provided with a level controller 39 which servesto automatically maintain a constant level somewhat above the lowerV endof conduit34 within the tank by actuating a valve 40 in vconduit 41which leads from the bottom of the tank. A vent' 33 to the atmosphere isprovided at the top of tank 33. Conduit 41 communicates with a pump 42which discharges through a conduit 43 into one or several run-down tanks44. A conduit 45 leads from near the bottom of run-down tanks 44 toconduit 41 with which it communicates at a point between valve 40 andpump 42.

A bottoms conduit 46 leads fromthe bottom of atmospheric tower 20 to abottoms pump 47 the discharge of which is connected by means of aconduit 48 to a second oil heater 49. A conduit 50 leads from heater 49to within a vacuum fractionating tower 5l. Tower 51 may be similar toatmospheric tower 20 and is provided with a nonmetallic lining 52 andwith cast iron bubble trays and stripping sections. The vacuum towerhere shown is provided with three stripping sections 53, 54 and 55 whichmay be supplied with superheated steam through a conduit 56 leading froma superheater placed in the setting of oil heater 49.

A conduit 57 communicates with the upper part of vacuum tower 51 andleads to a condenser 58 which is connected by means of conduit 59 with abarometric condenser 60 and a steam jet vacuum pump 61. The lower partof condenser 58 is connected by means of a conduit 62 with a cooler 63,which is connected by means of a conduit 64 with a vacuum run-down tank65. A conduit A66 leads from tank 65 to a reilux pump 67 which is inturn connected to the upper part of tower 51 by conduit 68. A pump isalso connected to vacuum rundown tank 65 by means of a conduit 91 anddischarges to storage through a conduit 92.

Side streams are withdrawn from stripping sections 53, 54 and 55 throughconduits 69, 70 and 71, respectively, to coolers 72, 73 and 74,respectively. These coolers are connected by means of conduits 75, 76and 77 with vacuum run-down tanks 78, 79 and 80, respectively. A conduit81 having branch conduits 82, 83 and 84 connects the vacuum run-downtanks with conduit 59. Pumps 85, 86 and 87 serve to pump liquid fromvacuum run-down tanks 78, 79 and 80, respectively, to storage. Thebottoms are withdrawn from tower 51 through a conduit 93 by a pump 94and pumped through a conduit to storage or waste.

The operation of the above described apparatus is substantially asfollows: I

Crude sulphur bearing oil is supplied to mixing tank 10 through conduit13. A suitable catalytic agent, such as clay or fullers earth or thelike is introduced into tank 10 and thoroughly mixed with the crude oilby means or stirrers 1l. Hereinafter in this specification the catalyticagent will be referred to as clay as a matter of convenience. Themixture of oil and clay is pumped from tank 10 by means of pump 16 intoheater 18 where the oil is gradually heated to around 800 degrees F. andthe lighter fractions arevaporized. As the diiierent fractions passthrough the zone of progressively increasing temperature in the heaterfor the desulphurization of that particular fraction, suchdesulphurization takes place due to the presence of the clay, theresulting liberated sulphur compound being hydrogen sulphide gas andvsome free sulphur. 'I'he vaporized fractions and the hydrogen sulphidepass with the remaining liquid and the clay into tower 20. The vaporspass upwardly through the bubble trays 26, and through differenttemperature zones within the tower. Different fractions of thedesulphurized oil are condensed to liquid form in different zones ofthe'tower as side streams from the strippingsections 27 and 27.

The tower is operated to discharge gasoline in vapor form from the topthereof through conduit 28, through which conduit also passes thehydrogen sulphide vapor and the steam. The temperature existing withinconduit 28 and beyond is well below 400 degrees F. and hence thehydrogen sulphide will not seriously attack the metal of conduit 28. Incondenser 29 the gasoline is condensed to liquid form and absorbs aconsiderable part of the hydrogen sulphide, and the resulting solutionpasses through conduit 30 to cooler 31. The steam may also be condensedand the resulting water absorbs some of the hydrogen sulphide, althoughthere is ordinarily not enough water for complete absorption. Aneutralizing agent, such as lime, may be introduced into conduit 30through conduit 30' and mixes to some extent with the solution ofhydrogen sulphide in gasoline and-is carried along therewith throughcooler 31 and conduit 32 into accumulator tank 33.

The purpose of this neutralizing agent is to neutralize the hydrogensulphide so that it may be separated as a harmless chemical from thegasoline fraction. A portion of the solution introduced into accumulatortank 33 is reuxed through conduit 34, reilux pump 35 and conduit 36 tothe top of tower 20 and flows downwardly therethrough over the bubbletrays therein and is again vvaporized by the hot gases passing upwardlythrough the tower. The remainder of the solution ows from the bottom oftank 33 through conduit 41 to pump 42. Pump 42 serves the double purposeof pumping liquid to one of the run-down tanks 44 and thoroughly mixingthe neutralizing agent with the solution of hydrogen sulphide Aingasoline so that the hydrogen sulphide will be completely neutralized.The neutralizing agent has a higher specific gravity than the gasolineand thus sinks to the bottom of tank`44 and is recirculated throughconduit 45 to pump 42. When one run-down tank 45 is illed, conduits 43and 44 are connected to the other run-down tank 44 and the contents ofthe rst tank 44 is allowed to stratify. 'I'he heavier neutralized orabsorbed hydrogen sulphide will collect in the bottom of the tank fromwhere it may be drawn 01T through conduit 44', leaving gasoline in tank44.

Kerosene is removed as a side stream through conduit 37 and may beconducted directly to storage while light gas oil drawn off as a sidestream through conduit 38 may be conducted to storage.

The heavier fractions of the original charge, which are not vaporized inheater 18, pass along with the clay downwardly over bubble trays 25 inthe lower part of tower 20 and form the bottoms which are withdrawnthrough conduit 46 and forced by means of pump 47 through conduit 48 tothe second heater 49. In heater 49 the oil and clay pass through a4second zone of increasing temperature. 'Ihe pressure in heater 49 isless than atmospheric due to the fact that a partialvacuum is maintainedin vacuum 4towelI 51 and hence a portion of the oil is vaporized anddesulphurized while passing through this zone. The vaporization takesplace in heater 49 at a lower temperature than would have been possiblein the flrst heater due to the lower pressure. From the heater the oil,hydrogen sulphide and clay pass through conduit 50 into vacuum tower 51.The oil vapor passes upwardly through a zone of decreasing temperaturein tower 51 where the heavier fractions are condensed and separated.

'I'he vacuum tower is operated to discharge heavy gas oil in the form ofa vapor from the top thereof and this gas oil passes along with thehydrogen sulphide resulting from the desulphurization process throughconduit 57 to condenser 58. The superheated steam introduced into tower51 may also pass through conduit 57 to condenser 58. In the condenseronly the gas oil is condensed while the steam and the hydrogen sulphidevapor pass through conduit 59 to barometricl condenser 60 and steam jetvacuum pump 61. The action of vacuum pump 61 is to maintain a vacuum intower 51 while barometric condenser 60 condenses the steam and alsoabsorbs the hydrogen sulphide vapors.

The liquid gas oil passes from the bottom of condenser 58 throughconduit 62 to cooler 63 and thence through conduit 64 to vacuum run-downtank 65. A portion of the liquid gas oil is refluxed from tank 65through conduit 66, through reflux pump 6'7 and conduit 68 to the upperpart of tower 51 to serve as reflux liquid for forming liquid seals onthe bubble trays. The remaining gas oil is pumped from tank 65 by pump90 to storage.

Side streams of light wax distillate, heavy wax distillate andlubricating oil are removed from stripping sections 55, 54 and 53,respectively, and are conveyed through the respective coolers to vacuumrun-down tanks 80, 79 and 78, respectively, from which they are pumpedto storage. The bottoms from tower 51 include the clay originallyintroduced in tank 10 and are removed by pump 94. The clay may bereclaimed from the bottoms and used again, but this is not ordinarilyprofitable and the bottoms are usually run to coke or used as fuel.

Inasmuch as the boiling point of light gas oil *is approximately 5'70degrees F. under atmospheric conditions, and the desulphurizationtemperature is approximately 700 degrees, the gas oil will be in thevapor phase at '700 degrees and hence may be desulphurized underatmospheric pressure. The boiling point and desulphurization temperatureof the heavy gas oils are. about the same and hence in order to getcomplete desulphurization it is necessary that, as to the heavierconstituents, the process be performed under a partial vacuum in orderthat the heavy gas oils vlwill be in the vapor phase. The boiling pointof the heavy wax distillate is below the desulphurization temperature atatmospheric pressure and hence it is absolutely necessary, in order tohave them in the vapor phase, to carry out the desulphurization stepunder vacuum. Hence, the di viding line between the fractions which maybe desulphurized at atmospheric pressure and thost that require vacuumappears to fall between the light and heavy gas oils but my invention isnot limited to such a line of demarcation, as this may vary withdifferent kinds of crude oil used.

It will be seen that in the desulphurizing and fractionating process theoil passes first through a zone of increasing temperature in the firstheater and then through a zone of decreasing temperature in theatmospheric tower while un; der a relatively hgh pressure todesulphurize and fractionate the lighter fractions. The heavierfractions which remain unvaporized are passed through a zone ofincreasing pressure in the second heater and then through a -zone ofdecreasing temperature in the vacuum tower while under a relatively lowpressure to desulphurize and fractionate these heavier fractions.

Whle I have advanced the theory that the desulphurization takes placeprogressively as to temperature for different fractions, it is to beunderstood that the correctness of the theory does not affect thevalidity of this patent.

The scope and breadth of my invention is to be limited only by theappended claims viewed in the light of the prior art.

What I claim is:

l. The method of fractionating sulphur bearing oil which comprisesmixing a catalytic agent with the oil, passing the mixture of oil andcatalytic agent 4through a zone of progressively increasing temperatureto eiect vaporization of a portion of the oil and to cause itsdesulphurization and the formation of a gaseous sulphur compound,passing the oil, catalytic agent and sulphur compound into anatmospheric fractionating tower having a non-metallic lining,withdrawing liquid oil and catalytic agent from the lower part of said tower,separating fractions of the oil introduced in vapor form in said tower,withdrawing the gaseous sulphur compound from the upper part of thetower, passing the mixture of oil and catalytic agent withdrawn fromsaid atmospheric tower through a second zone of progressively increasingtemperature under a relatively lower pressure `than the pressure offirstmentioned zone to effect vaporization of the oil and to cause itsdesulphurization and the formation of a gaseous sulphur compound,passing the oil and sulphur compound into a vacuum fractionating towerhaving a non-metallic lining, maintaining a partial vacuum in saidtower, separating fractions of the oil in the tower and withdrawing thegaseous sulphur compound from said tower.

2. The method of fractionating sulphur bearing oil which comprisesmixing a catalytic agent with the oil, passing the mixture of oil andcatalytic agent through a zone of progressively in- -creasingtemperature to effect vaporization of a portion of the oil and to causeits desulphurization and the formation of a gaseous sulphur compound,passing the oil, catalytic agent and sulphur compound into anatmospheric fractionating tower having a non-metallic lining,withdrawing liquid oil and catalytic agent from the lower part of saidtower, separating fractions of the oil introduced in vapor form in saidtower, withdrawing the gaseous sulphur compound from the upper part ofthe tower, passing the mixture of oil and catalytic agent withdrawn fromsaid atmospheric tower through a second zone of progressively increasingtemperature under a relatively lower pressure than the pressure of thefirst-mentioned zone to effect vaporization of the oil and to cause itsdesulphurization and the formation of a gaseous sulphur compound,passing the oil and sulphur compound into a vacuum fractionating towerhaving a non-metallic lining, maintaining a partial vacuum in saidtower, separating fractions of the oil in the tower, withdrawing a lightfraction of oil in vapor form and the gaseous sulphur compound from saidtower and separating the sulphur compound from said light fraction. l

3. Apparatus for the rening of sulphur bearing oil comprising, incombination, a tank, means to supply oil to said tank, mixing means insaid tank for mixing the oil with a catalytic agent, a heater, means toconduct oil and catalytic agent from said tank to said heater, means toheat the oil and catalytic agent in said heater to partially vaporizethe oil in the presence of the catalytic agent and to thereby form agaseous sulphur compound, an atmospheric fractionating tower having aceramic lining, means to convey the oil, catalytic agent and sulphurcompound from said heater to said tower, means to remove liquid oil andcatalytic agent from the lower part of said tower, means to condensefractions of the vaporized oil in said tower, means to convey a vaporousfraction of oil and the sulphur compound from said tower, means toseparate the sulphur compound from said oil fraction, means to conveythe liquid oil and catalytic agent removed from the lower part of saidatmospheric tower to a second heater, means to heat the oiland'catalytic agent in said second heater to vaporize the oil in thepresence of the catalytic agent and to thereby form a gaseous sulphurcompound, a vacuum fractionating tower having a ceramic lining, means tomaintain a partial vacuum in said tower, means to convey the vaporizedoil, catalytic agent and sulphur compound to said vacuum tower, means toseparate fractions of oil having different boiling points in said tower,means to convey a vaporous fraction of oil and the sulphur compound fromsaid tower and means to separate the sulphur compound from said oilfraction.

4. -Apparatus for the refining of sulphur bearing oil comprising, incombination, a tank, means to supply oil to said tank, mixing means insaid tank for mixing the `oil with a catalytic agent, a heater, means toconduct oil and catalytic agent from said tank to said heater, means toheat the oil and catalytic agent in said heater to partially vaporizethe oil in the presence of the catalytic agent and thereby form agaseous sulphur compound, an atmospheric fractionating tower having aceramic lining, means to convey the oil, catalytic agent and sulphurcompound from said heater 'to said tower, means to remove liquid oil andcatalytic agent from the lower part of said tower, means to condensefractions of the vaporized oil in said tower, means to convey a vaporousfraction of oil and the sulphur compound from said tower, means toseparate the sulphur compound from said oil fraction, means to conveythe liquid oil and catalytic agent removed from the lower part of saidatmospheric tower to a second heater, means to heat the oil andcatalytic agent in said second heater to vaporize the oil in thepresence of the catalytic agent and to thereby form a gaseous sulphurcompound, a vacuum fractionating tower having a ceramic lining, means tomaintain a partial vacuum in said tower, means to convey the 'vaporizedoil, catalytic agent and sulphur compound to said vacuum tower, means tointroduce steam into said tower, means to separate fractions of oilhaving different boiling points in said tower, means to convey avaporous fraction of oil, steam and the sulphur compound from saidtower, and means to separate the sulphur compound from the oil fraction,said last mentioned means comprising a barometric condenser.

5. Apparatus for the rening of sulphur bearing oil comprising, incombination, a tank, means to supply oil to said tank, mixing means insaid tank for mixing the oil with a catalytic agent, a heater, means toconduct oil and catalytic agent from said tank to said heater, means toheat the oil and catalytic agent in said heater to partially vaporizethe oil in the presence of the catalytic agent and thereby form agaseous sulphur compound, an atmospheric fractionating tower having aceramic lining, means to convey the oil, catalytic agent and sulphurcompound from said heater to said tower, means to remove the liquid oiland catalytic agent from the lower part of said tower, means to condensefractions of the vaporized oil in said tower, means to convey a vaporousfraction of oil and the sulphur compound from said tower, means toseparate the sulphur compound from said oil fraction, means to conveythe liquid oil and catalytic agent removed from the lower part of saidatmospheric tower to a second heater, means to heat the oil andcatalytic agent in said second heater to vaporize the oil in thepresence of the catalytic agent and to thereby form a gaseous sulphurcompound, a vacuum fractionating tower having a ceramic lining, means tomaintain a partial vacuum in said tower, means to convey the vaporizedoil, catalytic agent and sulphur compound to said vacuum tower, means tointroduce steam into said tower, means to separate fractions of oilhaving different boiling points in said tower, means to convey avaporous fraction of oil, steam and the sulphur compound from saidtower, and means to separate the sulphur compound and the steam from theoil fraction, said last mentioned means comprising a barometriccondenser.

6. Apparatus for the rening of sulphur bearing oil comprising, incombination, a tank, means to supplyy oil to said tank, mixing means insaid tank for mixing the oil with a catalytic agent,A

a heater, means to conduct oil and catalytic agent from said tank tosaid heater, means to heat the oil and catalytic agent in said heater topartially vaporize the oil in the presence of the catalytic agent andthereby form a gaseous sulphur compound, an atmospheric fractionatingtower having a ceramic lining, means to convey the oil, catalytic agentand sulphur compound from said heater to said tower, means to remove theliquid oil and catalytic agent from the lower part of said tower, meansto condense fractions of the vaporized oil in said tower, means toconvey a vaporous fraction of oil and the sulphur compound from saidtower, means to separate the sulphur compound from said oil fraction,means to convey the liquid oil and catalytic agent removed from thelower part of said atmospheric tower to a second heater, means to heatthe oil and catalytic agent in said second heater to vaporize the oil inthe presence of the catalytic agent and to thereby form a gaseoussulphur compound, avacuum fractionating tower having a ceramic lining,means to maintain a partial vacuum in said tower, means to convey thevaporized oil, catalytic agent and sulphur compound to said. vacuumtower, means to introduce steam into said tower, means to separatefractions of oil having different boiling points in said tower, means toconvey a vaporous fraction of oil, steam and the sulphur compound fromsaid tower, means to liquefy the vaporous oil fraction and means toseparate the sulphur compotmd the oil fraction, said last mentionedmeans comprising a barometric condenser.

catalytic agent in said heater to partially vaporize` the oil in thepresence of the catalytic agent and vthereby form a gaseous sulphurcompound. an

atmospheric fractionating tower having a ceramic lining, means to conveythe oil, catalytic agent and sulphur compolmd from. said heater to saidtower, means to remove the liquid oil and catalytic agent from the lowerpart ci said tower, means to condense fractions of the vapor-ized oil insaid tower, means to convey a vaporous frac-y tion o oil and the sulphurcompound from said tower, means to separate the sulphur compound fromsaid oil fraction, means tov convey the liquid oil and catalytic agentremoved from the lower part of said atmospheric tower to a secondheater, means to heat the oil and catalytic agent in said second heaterto vaporize the oil in the presence of the catalytic agent and tothereby form a gaseous sulphur compound, a vacuum fractionating towerhaving a ceramic lining, means to maintain a partial vacuum in saidtower, means to convey the vaporized oil, catalytic agent and sulphurcompound to said .vacuum tower, means to introduce steam into saidtower, means to separate fractions of oil having different boilingpoints in said tower, means to convey a vaporous fraction of oil, steamand the sulphur compound from said tower, means to liquefy the vaporousoil fraction and means to separate the sulphur compound and the steamfrom the oil fractiomsaid last mentioned means comprising a barometriccondenser.

8. Apparatus for the rening of oil comprising, in combination, a tank,mixing means within said tank, a heater, a conduit connecting said tankwith said heater, a fractionating tower, a conduit connecting saidheater with said tower, a nonmetallic lining in said tower, a condenser,a conduit connecting the upper part of said tower with said condenser, asecond tank, a conduit connecting said condenser with said second tank,a conduit communicating with said last mentioned conduit, a run-downtank, a conduit connecting said second tank with said run-down tank, apump interposed in said last mentioned conduit and a conduit connectingthe'lower part o! said rundown tank with said last mentioned conduit ata point between said second tank and said pump.

9. The method of fractionating sulphur bearing oil which comprisesmixing a catalytic agent with the sulphur bearing oil, passing themixture of oil and catalytic agent through a zone ci progressivelyincreasing temperature to vaporize and desulphurize a portion of the oilin said zone, passing all of the mixture so heated into a zone ofprogressively decreasing temperature to separate fractions of thedesulphurized oil, passing the portion of the oil not vaporized and thecatalytic agent through a zone of progressively increasing temperatureat a relatively lower pressure than the pressure of the rst zone tovaporize and desulphurize a portion of the oil and passing all of thelast heated mixture into a zone of progressively decreasing temperatureto separate fractions thereof.

JOHN H. ER'I'YER.

